Chronic obstructive pulmonary disease

Effective management of COPD should preserve lung function and control exacerbations, says Dr Laurence Knott.

The term COPD embraces patients formerly diagnosed with chronic bronchitis and/or emphysema. The main feature is airflow limitation that is not fully reversible.

The prevalence of COPD is usually quoted as 1-2 per cent. However, a study conducted by the GP research unit in Manchester found an overall prevalence of 4.1 per cent.

Risk factors include smoking, occupational exposure to noxious gases and particles, and hereditary alpha1-antitrypsin deficiency.

Signs and symptoms
COPD should be considered in any patient over 35 with a history of smoking and respiratory symptoms, especially breathlessness on exertion, productive cough, frequent chest infections or wheezing. A history of weight loss or ankle oedema may also be significant.

Signs of respiratory distress may be present, with a fast respiratory rate, breathlessness on exertion, use of the accessory muscles of respiration and pursed lips when breathing.

If carbon dioxide retention is a significant feature, the patient may be drowsy with a flapping tremor and mental confusion.

Thoracic examination may reveal hyperinflation (barrel chest) with hyper-resonance on percussion, reduced breath sounds, prolonged expiration, wheezing and crackles.

In advanced disease there may be cyanosis, elevated jugular venous pulse, peripheral oedema, and downward displacement of the liver.

Diagnosis
Spirometry is key to the diagnosis of COPD. The diagnostic criteria are:

  • Reduced FEV1 (<80 per cent predicted) after bronchodilation together with a reduced FEV1/FVC ratio (<70 per cent)
  • Little or no reversibility of airflow obstruction
  • Alpha1-antitrypsin deficiency should be considered in young patients without a history of smoking.

NICE recommends that all suspected COPD patients should have their BMI calculated (low BMI is a bad prognostic sign), a chest X-ray to rule out other respiratory diseases (for example, pulmonary TB, lung cancer) and an FBC to exclude anaemia and polycythaemia secondary to chronic hypoxia.The NICE guidelines adopt the following classification of severity:

  • 50-80 per cent predicted FEV1 = mild
  • 30-50 per cent predicted FEV1 = moderate
  • Less than 30 per cent predicted FEV1 = severe

Management
All patients who smoke should be offered cessation advice, and pneumococcal and influenza vaccination. Pulmonary rehabilitation and dietetic advice may also be appropriate.

GPs should be alert to the presence of anxiety and depression in patients with COPD.

Drug treatment of stable COPD focuses on suppressing symptoms and reducing exacerbation. No treatment has been discovered that will halt the long-term decline in lung function.

Stepwise approach

NICE guidelines recommend the following stepwise approach:

  • Use short-acting bronchodilator (beta-2 agonist or anticholinergic) as required.
  • If symptoms persist, use combined therapy of short-acting beta-2 agonist and short-acting anticholinergic.
  • If symptoms persist, use long-acting bronchodilator (beta-2 agonist or anticholinergic).
  • If symptoms persist, consider a four-week trial of combination long-acting beta agonist with inhaled corticosteroid. Discontinue if no benefit after four-weeks.
  • If symptoms persist, consider adding theophylline, which can improve FEV1.

There is evidence that anticholinergics are more effective bronchodilators than beta-2 agonists in COPD. Inhaled ipratropium four times daily has been the first-line drug for many years.

Tiotropium, which is given once daily, is indicated in patients who fail to respond to short-acting beta-2 agonist plus ipratropium; there is some evidence that tiotropium is superior in reducing exacerbations and hospital admissions.

Mucolytics such as carbocysteine may reduce the frequency of exacerbations.

Long-term oxygen may be helpful, but should be initiated by a specialist.

Exacerbations
Most patients can be managed at home but hospital admission should be considered if there is severe breathlessness, cyanosis, peripheral oedema, reduced consciousness or adverse social circumstances. NICE recommends:

  • Short-acting bronchodilators given in high dose (a spacer device is as effective as a nebuliser).
  • Oral steroids 30mg once daily for 7-14 days (there is no advantage in giving for longer; consider osteoporosis prophylaxis in patients on regular courses).
  • Antibiotics - only appropriate if the sputum is purulent or consolidation is evident (amoxicillin, erythromycin or tetracycline). Be guided by local policy. Sputum culture may be helpful in due course, but do not wait for the results before starting treatment.
  • Oxygen is recommended, even in the absence of blood gases or oximetry.
  • In secondary care, non-invasive and invasive ventilation, respiratory stimulants such as doxapram, and intravenous theophylline may be considered.

Surgery
Surgery may be appropriate for patients who are dyspnoeic despite maximal medical therapy. Options include bullectomy, lung volume reduction surgery and lung transplantation.

Palliative care
Palliative care is as relevant in end-stage COPD as in patients with cancer. Options include opiates to improve breathlessness, benzodiazepines, tricyclic antidepressants, major tranquillisers, oxygen, palliative nursing care and hospice admission.

Prognosis
Complications of COPD are cor pulmonale, pneumothorax, respiratory failure, arrhythmias and secondary polycythaemia. The decline in lung function is variable, and is slowed by control of exacerbations.

The mortality rate is 24 per cent in patients admitted to an ICU with an acute exacerbation; this doubles for patients aged 65 years or older.

Dr Knott is a GP in Enfield, London

Differential diagnoses
Differential diagnoses include:
Asthma

  • Allergic fibrosing alveolitis
  • Alpha1-antitrypsin deficiency
  • Congestive heart failure
  • Hypersensitivity pneumonitis
  • Pneumoconiosis
  • TB
  • Lung cancer

Key Points

  • The quoted prevalence of COPD is 1-2 per cent but this is likely to be underestimated.
  • Smoking is the chief risk factor.
  • The goal of management is to suppress symptoms and reduce the frequency of exacerbations.
  • Most exacerbations can be managed at home, but hospital admission should be considered if symptoms are severe.
  • Palliative care should be considered for patients with end-stage COPD.
  • The prognosis is improved by prevention of exacerbations.

References

  • Frank T, Hazell M, Linehan M et al. The estimated prevalence of chronic obstructive pulmonary disease in a general practice population. Prim Care Respir J 2007; 16:169-73.
  • NICE clinical guideline; CG12 - Chronic obstructive pulmonary disease, 2004.
  • Prodigy Clinical Knowledge Summary. Chronic obstructive pulmonary disease, 2006.

 

 

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